How High the Rez?

How high is high-resolution? How stereo is stereo? How many bits are really dancing around inside your DAC? How much wood did the marmot masticate?

We’ve all worried about these questions, in the dark nights of the soul that afflict so many audiophiles—especially after that second chili-dog. Well, finally we can do something about them, or at least three out of four, thanks to a brilliant new Mac/Windows application called MusicScope, fresh from the fertile fields of Düsseldorf.

Available in both Windows and Mac OSX versions (my experience is with the latter), MusicScope can answer all of the above questions and many more. Like countless other programs, MusicScope paints an audio spectrogram display. But that’s just the icing: the cake itself is baked into its many other data representations, which include a stereo x/y “scope,” bar-graph meters of conventional and mid/side channel levels, including both peak and crest-factor display options, a bit-monitor, and a great deal more. If you’re a true audio-geek, I can promise you many hours of wholesome fun. (If not, MusicScopes colorful bouncing, pulsing, spreading displays are sure to impress members of whatever gender(s) engage your interest.)

Anyway, it’s a very cool program. The free demo only lets you analyze 30 seconds of any given file, but a full license costs less than 25 Euros which, given the dollar’s Sherman-like march through Europe lately, seems likely by the time you read this to be the equivalent of a hamburger next Tuesday.

Obviously, there’s a lot MusicScope can tell us. But a picture is worth a thousand words—two thousand, if they’re coming from an “audio journalist” (one of my favorite oxymorons). So let’s have a peek:

This is a screen-capture of MusicScope’s analysis of a portion of a “high-resolution audio,” DSD-64 orchestral recording. You need not squint out all the details from this small image: just focus on the linear spectrum display, the squiggly, yellow-gold line stretching full-width across the middle of the window: this shows peak levels reached at all frequencies, sort of like an multi-band bouncing-bar real-time analyzer, but with infinitely many bands. The horizontal axis is frequency in kHz; we can clearly see the familiar pattern of a music waveform beginning at the far left (20 Hz) and stretching rightward to the blue vertical cursor, which I’ve positioned at about 23 kHz. Beyond this point, the line changes to a random noise-spectrum shape, and assumes the familiar parabolic form of the up-shifted noise-shaping spectrum I’d expect from any 1-bit recording.

My conclusion? This particular HRA file has no meaningful content above, 22 kHz or so, which strongly suggests that, hi-rez or not, DSD-format and all, it almost certainly originated (or at least passed) through a 44.1 kHz-sample-rate format—most likely a 16-bit compact disc or CD master.

I now present a second picture, superficially identical to the first, produced from a different DSD-64 hi-rez file (this one was chamber music, not that that matters very much):

I’ve placed the blue cursor at the same transition-point separating the recognizable music waveform and the noise-shaping spectrum; in this case, it’s about 35 or 40 kHz, which is consistent with an 88.2 kHz-sampled DSD master. So this file, at least, certainly appears to have been more fairly characterized as a high-resolution audio recording.

Note that I didn’t say it sounded “better”—or even different. That’s a tree of another color falling in an altogether different forest, and I ain’t going there. Not today. Not tomorrow, neither.

MusicScope, however, is an unalloyed winner in my view. Mess around with it for an hour or two and I’m pretty sure you’ll purchase the full version. I hope you do: these guys deserve it.

Brown Sound's picture

Thank you for pointing this program out. It works great at verifying a file's resolution. Plus it is a hoot to watch!

kevon27's picture

Hey, dude.. That stuff you see after 35khz is NOTHING BUT NOISE... Worthless nothing.. It's an artifact of DSD.
The amplitude of the information past 20khz is very, very low - inaudible..
97% of the stuff that is labeled Hi-res is nothing more than SD (tape/cd/vinyl) rips and converted to a hi-res file.
I can take a old cassette tape, use a ADC to capture the analog audio and a convert create a file to a 32 bit/ 384 kHz file... IS THAT MAXELL cassette conversion now hi-res? NO..

Daniel Kumin's picture
Agreed. The point is (or was), that the LF origin of the noise-shaping curve pretty strongly suggests the upper limit of the source, and thus the Nyquist frequency of the digital recording system employed.